My invention relates generally to filters, to solid-liquid filters, and particularly to a dynamic filter apparatus particularly well suited for the separation of slurries into a solid and a liquid. More particularly, my invention concerns improvements in a dynamic filter apparatus of the type having a plurality or multiplicity of rotary filter discs.
Japanese Laid Open Patent Applications Nos. 47-23949 and 47-26758 suggest slurry filters which, as far as I am aware, represent the prior art closest to my invention. Both of these known filters comprise a plurality of rotary filter discs nonrotatably mounted on a hollow shaft at constant longitudinal spacings, and a plurality of stationary filter discs arranged alternately with the rotary filter discs.
I object to these prior art devices because of a rapid decrease in the flow rate of the slurry through the meandering path between the rotary and fixed filter discs upon decrease in the water content of the slurry with the progress of filtration. Such a decrease in the flow rate of the slurry results in an increase in the load both on the drive motor revolving the rotary filter discs via the hollow shaft and on the pump for forcing the slurry into the filter apparatus. These problems have so far been circumvented by employing a drive motor and pump of large capacities at considerable expenses. The pumping of the slurry under increased pressure represents no satisfactory solution because of the need for the frequent replacement or repair of the seals, as well as of difficulties encountered in the removal of the cake that has stuck fast to the filter discs.